Arduino Capitative Sensor overheating

Hi, Im currently creating a fingerprint-based safe using a capitative fingerprint sensor connected to an Arduino UNO. It was working for a while, but then suddenly the fingerprint sensor started overheating. It still worked, but became extremely hot.

My connections are as follows:
VCC -> 3.3v
GND->GND
Rx->3
Tx->2

My code is simply the example code for the DFRobot Arduino Module (Fingerprint Registration).

That suggests CMOS latch-up, which normally cooks a chip unless the power is removed rapidly.

The usual way latch-up happens is via phantom powering, or a large current injected into an input that overwhelms the protection diodes.